Given, for example, legislation arising from the global warming problem, there are demands for strengthened control of the quantity of energy used in factories and manufacturing lines. Because heat-producing equipment and air-conditioning equipment are facilities equipment that can consume a particularly large quantity of electricity, often the upper limit for the quantity of energy consumed is controlled so as to be kept lower than the maximum value in conventional equipment. For example, in facilities equipment that runs on electric power, the operations are performed in particular so that the quantity of electricity used will be within specific limitations prescribed by an electric power demand controlling system.
In particular, there have been proposals for methods, such as for electric power overall suppression and control, for limiting the total quantity of electric power that is supplied simultaneously at the time of startup in heat-producing equipment that is provided with a plurality of electric heaters (when heating up simultaneously the temperature in multiple areas wherein electric heaters are installed). See, for example, Japanese Unexamined Patent Application Publication 2012-048533 (“the JP '533”). FIG. 12 is a block diagram illustrating the structure of a heating device disclosed in the JP '533. The heating device includes a heat treatment furnace 100 for heating an object to be heated, heaters H1 through H4, which are a plurality of control actuators disposed within the heat treatment furnace 100, a plurality of temperature sensors S1 through S4 that measure the temperatures of regions that are heated by the respective heaters H1 through H4, a higher-level controller 101 of a total electric power limiting/controlling device for calculating operating volumes MV1 through MV4 to be outputted to the heaters H1 through the H4, a lower-level controller 102 of the total electric power limiting/controlling device, and electric power regulators 103-1 through 103-4, for providing to the respective heaters H1 through H4, electric power in accordance with the operating volumes MV1 through MV4 that are outputted from the lower-level total electric power limiting/controlling device 102.
The higher-level controller 101 of the total electric power limiting/controlling device receives information for a total allocated power PW that specifies the total amount of power used by the heaters H1 through H4, from a higher-level PC 104 that is a computer of a power demand managing system that manages the electric power, and then calculates the total amount of power used TW, which is the sum of the power used by the individual heaters H1 through H4, and then calculates operating volume upper limit values OH1_1 through OH1_4 for the individual control groups so that the total amount of power used TW does not exceed the total allocated power PW.
The lower-level controller 102 of the total power limiting/controlling device is structured from temperature controllers C1 through C4, which are structured from a plurality of control loops Ri (where i=1 through n), where, in the example in FIG. 12, the number n control loops is n=4. The individual temperature controllers C1 through C4 calculate the operating volumes MV1 through MV4 using, for example, respective PID control calculations, to execute upper limit limiting procedures to control the operating volumes MV1 through MV4 so as to be no higher than the operating volume upper limit values OH1_1 through OH1_4, and output, to the electric power regulators 103-1 through 103-4 of the corresponding control loops, the operating volumes MV1 through MV4 after the upper limit limiting procedures. Doing so achieves the limiting of the total electric power through the operations of the operating volume upper limit values OH1_1 through OH1_4 of the temperature controllers C1 through C4.
In the total electric power limiting/control disclosed in the JP '533, an ordinary temperature controller can be used as the lower-level controller 102. That is, this is an easy approach at instrumentation for the device manufacturer.
Note that in an ordinary temperature controller, within the temperature controller there is only one type of operating volume lower limit value OL and operating volume upper limit value OH, set by the user. Despite the fact that there are sometimes a plurality [of operating volume lower limit values OL and operating volume upper limit values OH] that are switched in coordination with the setting value SP (which is a temperature setting value for the case of temperature control) or the control variable PV (which is a temperature measurement value in the case of temperature control), this still does not change the fact that, as a type, there is only one type that is user-settable in the temperature controller. Moreover, while there are also those controlling devices that store, in a special area in memory, an operating volume lower limit value OL and an operating volume upper limit value OH for use only by the auto-tuning function for adjusting the PID parameters, this memory area, in the end, is used exclusively when performing auto-tuning See, for example, Japanese Unexamined Patent Application Publication 2003-330504 (“the JP '504”). That is, during the execution of PID control, two types of operating volume lower limit values OL and operating volume upper limit values OH are not provided simultaneously as candidates for application.
As described above, in an ordinary temperature controller, there is only one type of memory area for the operating volume lower limit value OL and the operating volume upper limit value OH, set by the user in the temperature controller. Consequently, when using a temperature controller as the lower-level controller 102 in, for example, the total energy limiting/control disclosed in the JP '533, there is no choice but to have the higher-level side monopolize the use of that single type of memory area for the operating volume lower limit value OL and the operating volume upper limit value OH. In the total power limiting/control disclosed in the JP '533, the procedure is one wherein the higher-level controller 101 ascertains in advance the operating volume upper limit value OH that normally would be set in the lower-level controller 102. For this reason, even if the operating volume lower limit value OL or the operating volume upper limit value OH is changed during the execution of control (after control has started) in the conditions in the lower-level controller 102, there may be transmissions for further changes from the higher-level controller 101 that assume an old (pre-change) operating volume upper limit value OH. That is, an operating volume upper limit value OH that has been updated by the lower-level controller 102 may be overwritten.
For example, let us assume that, when starting the total energy limiting/control disclosed in the JP '533, the operating volume upper limit value OH in the lower-level controller 102 is set to 100%. In the higher-level controller 101, this operating volume upper limit value OH=100% is registered in advance, so, based on this registration, the higher-level controller 101 sends, to the lower-level controller 102, a variable operating volume upper limit value OH of, for example, the operating volume upper limit value OH=90% or OH=80%. Given this, by overwriting the operating volume upper limit value OH in the memory area of the lower-level controller 102, the lower-level controller 102 will perform an upper limit limiting procedure for controlling the operating volume MV, calculated through the PID control calculations, so as to be no higher than the operating volume upper limit value OH.
At this time, let us assume that the operator of the lower-level controller 102 changes the operating volume upper limit value OH in the memory area of the lower-level controller 102 to 70%, given the circumstances on the lower-level side, through an operating panel of the lower-level controller 102 (the temperature controller). In an ordinary temperature controller, there is no function for constantly sending the operating volume upper limit value OH to the outside, and because the connections for the communication functions would be laborious if this were the standard instrumentation within the device, the modification of the operating volume upper limit value OH to 70% is not sent to the higher-level controller 101. In this case, the higher-level controller 101 would still assume the operating volume upper limit value OH=100% to calculate the operating volume upper limit value OH that is to be set in the lower-level controller 102, and thus the operating volume upper limit value OH calculated by the higher-level controller 101 would end up being written to the memory area of the lower-level controller 102. As a result, the limit of the operating volume upper limit value OH=70%, from the circumstances on the lower-level side, would be invalidated.
Note that temperature controllers are shipped from the temperature controller manufacturers to the device manufacturers, and the devices in which the temperature controllers are installed are shipped in large quantities from the device manufacturers to the end users. Because the temperature controller manufacturers, which are the control technology vendors, typically are the ones that take the lead, it is difficult, in practice, to get information all the way to the operators that are the end-users. Consequently, there are many cases wherein the operators on the lower-level side (the operators of the temperature controllers) do not know that there is the possibility that settings that are changed through the operating panel may be overwritten.
In methods wherein the operating volume lower limit value OL and the operating volume upper limit value OH are applied or determined by the higher-level side in this way, the actual purpose thereof, that of a procedure for limiting the operating volume MV, may be lost. The total power limiting/control disclosed in the JP '533 is a typical case of a control solution that uses the operating volume lower limit value OL and the operating volume upper limit value OH, and the problem areas described above are problem areas that are common to this type of control solution.
The present invention is created in order to solve the problem set forth above, and an aspect thereof is to provide a controlling device able to prevent invalidation of the limiting procedure that depends on the circumstances of the lower-level side when a control solution that uses an operating volume upper limit value and/or an operating volume lower limit value is performed by a device on the higher-level side.